It's another show of support by Wounded Warrior Stables for military veterans injured or killed in Afghanistan.
George "Chip" McEwen, a longtime horse owner, adopted his stable name two years ago and donates 10 percent of the horse's purse earnings to several veterans' organizations. First place in the Derby is worth $1.4 million.
"It's not about me, it's about them, and getting them in the forefront of people's minds again because it's easy to forget we've been at war since 2001," said McEwen, who owns Uncle Sigh in partnership with Anthony Robertson.
McEwen was moved to action several years ago after seeing a disabled veteran get helped off a flight.
"It was then that I realized that I had to do more for people like that than buy a wristband or a T-shirt to support them," he said.
He has invited several wounded veterans to join him at the Derby.
"We're excited to have them here," he said. "It's a special day for us and this horse. Every horse owner's dream is to get to the Derby. We're hoping for a miracle, like everybody else."
Uncle Sigh is 30-1 on the morning line. He is 1 for 5 in his career, running fifth most recently in the Wood Memorial. The colt wears blinkers to narrow his vision and filter out distractions.
Trainer Gary Contessa hopes adding the blinkers for the first time pushes Uncle Sigh to pull off McEwen's miracle.
"I think they'll help him take the next jump," Contessa said. "In every single race I've seen a reason to think he needs blinkers. Hopefully we'll focus him, and he can become a really good horse."
AN IRONIC SCRATCH: The irony of the situation was not lost on Bob Baffert after he scratched Hoppertunity from the Derby on Thursday.
The Hall of Fame trainer entered two horses in the Derby, Hoppertunity and Chitu, who has been battling a foot fungus.
Of the two, Chitu appeared most likely to miss the race, especially after he threw a custom-made shoe in a workout last weekend.
Only days from the Derby, Chitu is still in. Hoppertunity was the one who dropped out with an injured foot. He was the early 6-1 second choice and was to have been ridden Saturday by Hall of Fame jockey Mike Smith.
Chitu, the Sunland Derby winner, has a fungus infection in the right front foot. He has had the condition for some time and it has not hurt his performance. It requires special shoeing and treatment between races.
"It's a little fungus that gets in the toe and eats the front of the hoof wall," Baffert said. "It's not painful. He's never been sore."
Chitu is 20-1 with Martin Garcia set to ride.
Baffert said Hoppertunity could return in time for the Preakness on May 17.
Churchill Downs oddsmaker Mike Battaglia revised the Derby morning line odds, although California Chrome remained the favorite at 5-2.
Wicked Strong, the colt named for the victims of last year's Boston Marathon bombings, replaced Hoppertunity as the early second choice at 6-1.
The scratch moved also-eligible horse Pablo Del Monte into the maximum 20-horse field. However, the 50-1 shot would have to start from the No. 20 post position.